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Why do yawns seem contagious?

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Researchers at the University of Vienna tested subjects in Austria and Arizona

Sex, season, age, humidity, time spent outside, and amount of sleep did not have an effect

Chances are you read this sentence about yawning and you yawned. Right?

Well, a new study suggests that you may not really be yawning because it's contagious, or you're bored or tired.

You're actually yawning because your brain is too hot.

A group of researchers at the University of Vienna tested subjects in Austria and Arizona and tracked their activity, finding that that the only significant predicator of yawning was temperature: subjects were much more likely to yawn at higher temperatures.